Thermostat



March 27, 1945. WEBER 2,372,464

- THERMOSTAT Filed April 15, 1942 INVENTOR. VicToR WEBER.

Patented Mar. 27, 1945 UNITE.

THERMOSTAT Victor Weber,

Greensburz,

ia assignor to Robertshaw Thermostat Company, Young wood, Pa., acorporation of Pennsylvania Application April 15, 1942, SerialNo.439,149

' 2 Claims. (01.236-48) This invention relates to thermostat mechanismsand, more particularly, to those of the multi-lever snap-acting type.

An object of the invention is to permit manufacture and testing of thesnap-acting mechanisms as complete units apart from the thermojustmentbefore assembly.

Another object of the invention is to reduce the space required for theassembly by permit ting offset arrangement of the parts while retainingpositive action thereof.

Another object of the invention is torender the device simple andcompact and adapted for rapid assembly and relatively inexpensive tomanufacture.

Other objects and advantages will become apparent from the followingdescription taken in connection with the accompanying drawing,

'of Fig. II;

Fig. V is a. section taken on the line V-Jil of Fig.

Figs. VI to IX are perspective views of parts of the lever mechanism.

Referring more particularly to the drawing, the control body isgenerally rectangular in stat proper to assure uniform and accurateadform, having substantially the same width and thickness but of greaterlength, and is provided with an auxiliary portion l2 .on one sidethereof of less length than the main control body ill. The main body I9is open on theside opposite the auxiliary portion l2 and is providedwith a closure plate It secured thereto by means of the screws I6. Theopen side of the body lb does not extend for the full length of the bodybut terminates shcrtof one end thereof leaving a flange I8. An outlet isprovided in the end of the body I0 adjacent the flange i8 and may bethreaded or otherwise adapted for connectionv with a pipe leadingito theburner of the appliance with which the control isto be used.

. The auxiliary portion I2 is separated in part from the interior of themain body II) by a partition 22 whichextends lengthwise of the body l0and is provided with a recess 24 having a bottom wall 25 and a side wall28. The side wall 28 has an opening 30 therethrough providing accessbetween the recess 2t and a valve chamber 32 formed by the space betweenthe partition side wall 28 and the outer wall of the auxiliary portioni2 v The valve chamber 32 contains a. valve member 36 adapted to seatagainst the side wall 28 and control passage of fluid through theopening 3d. The valve member 341 is yielda'bly retained on its seat bymeans of a coil spring 36 extending between the valve member t t and acap 38 threadedly engaging with an opening in the outer wall of theauxiliary portion i2 and providing access to the valve member when thecap 38 is removed. A stem w projects from the valve member into a stemguide 42 projecting from the cap 38 and the valve member may further beproyided with a projection 44 extending opposite the valve stem throughthe opening 39 and into the recess 26. 4

That portion of the auxiliary body l2 separated from the main body it bythe bottom Wall 26 of the partition forms an inlet chamber 66 with whicha pair of angularly disposed inlet penings t8 communicate. The inletopenings 48 may be threaded or otherwise adapted for connection withpipes leading from a source of fuel supp y. It will be apparent thatonly one such inlet as could be provided and only one is required to be-chosen for connection purposes but greater flexibility in installationis provided by the arrangement described. Due to the provision of thepartition 22 which, as stated, extends throughout the length of the bodyIII, the only Path of communication between the inlet 48 and outlet 20is from the chamber d6 through the opening 30, controlled by the valvemember 34, and into the recess 24 to the interior of the main body I0,with which the outlet 28 communicates.

The burner of the appliance which receives fuel from the outlet 20operates in response to a thermostat carried by a boss 50 projectingfrom the main body ID on the side opposite the cap 38. The thermostatshown is of the rod-and-tube type, such as may be inserted in thestorage tank of a water heating system with which the burner isassociated.v The tube 52 of the thermostat of this embodiment has a highcoeiiicient of expansion and is mo tea at its inner end in a threadedopening 54 of the boss 50. The rod 53 of the thermostat, which maybe oiinvar or other materialhaving a low coe flicient of expansion, extendswithin the tube 52 and abuts a plug 58 threaded or otherwise secured inthe end of the tube 52. The opposite end of the rod 56 abuts one end ofa pin 60 which is slidable in the wall of the main body I and projectsinto the interior thereof. The rod 56 is supported in the tube 52 byspaced projections 6| extending-into slidable engagement with theinterior surface of the tube.

The thermostat is adapted to operate, upon' cooling of the water irr'thestorage tank of the water heater, by movement of the rod 56 to the rightfrom the position shown in Fig. III, due to I2 carried by the frame 62.This lever I6 is channel-shaped and has part of its base removed,leaving an opening at the central portion there? of with spaced barportions 83 and SI respective- 5 ly at each end connected by arms 93 atthe sides.

with-the thermostat is provided by a stem 90,

contraction of the tube 52, which opens the valve 34-through theinterposition of suitable multilever snap acting mechanism. Conversely,when the temperature in the storage tank increases,

the tube 52 expands, permitting the rod 56 to move toward the left tothe position shown in Fig. III, causing movement of the valve member 34to closed position through the same snap-acting means.

The bar portion 89 has its outer edge seated in the fulcrum seat 14 ofthe frame 62 as previously mentioned, a knife-edge bearing beingprovided on this edge. Operative engagement of the lever having arounded end seated in a depression 92 formed inthe central portion ofbar 89 of lever 16 and having its opposite end abutting the pin 60. Thepin 90 is slidably mounted in a'bearing 15 portion 94 carried by thedepending arm 96 of an angular stop plate 98 which is secured by meansof the screws I00 to the flange I2 of the frame.

The width between the arms 93 of the thermostat lever I6 is sumclentlyless than that'between the arms 64 of the frame 62 to provide a spaceThe multi-lever snap-acting. mechanism of this invention is entirelyself-contained and. may be assembled and tested apart from the controlbody I0. The mechanism comprises aframe 62, upon which all of the leversare'mounted, and which has opposite arms 64 connected at one end of theframe by a tubular element 66. The element 66 is adapted for engagementat its opposite ends with a pair of pivots 68 carried by the flange I8 Iand the opposite side wall of the body I0, respectively. The arms 64 arealso connected by a back portion I0 which may be integral with the arms64 and extends from the end opposite the tubular element 66 andterminates short'of this element. The portion I0 is provided with aflange I2 extending between the arms 64 at the end 0D- for theaccommodation of the arms I02 of a valve operating lever I04. These armsI02 are connected at their upper portion by a. bar I06 extending betweenthe thermostat lever I6 and arm 96 of the stop plate. The bar I06 has arecessed erally from the bar portion I06 across one arm portion I08centrally disposed on its underside and a depressed bearing portion I I0on the opposite side, the purpose of which will appear here- .inafter. Avalve operating-arm II2 projects lat- 64 of the frame 62. Theoperatingarm H2 is of sufficient length to project into the recess 24 of theauxiliary body portion. I2'when the-parts are assembled in the controlbody and carries a tip II4 which engages with the projection 44 ofposite-the tubular element 66 andbeing provided with a notched portion"forming a fulcrum seat for a thermostat lever 16. The flange 12 isretained against displacement from its position between the arms 64 byshort projections I8 formed on the arms 64 and overlying part of theflange I2 for this purpose.

I The pivots 68 which engage with the tubular element 66 015 the frameare preferably in the form of screws having threaded engagement with thecontrol body I0 and being adjustable from. the exterior thereof. In thimanner, the pivots the valve member 84.

The bar portion 9| constituting the free end of the thermostat lever 16is provided with a depressed bearing portion I I6 similar to the bearingportion H0 and adapted to accommodate one hook end II8 of a coil springI20, the other hook end I22 of which engages with the bearing portionIIO of the lever I04. The spaced ends of the arms I02 of .the valveoperating lever l04 are provided with"suitable knife-edge bearing per-68 may readily be removed from engagement with the tubular element 66and upon removal of the closure plate I4, the frame 62 and associatedparts may be removed as a unit from the control body. Furthermore, sucharrangement permits adjustment of the-frame 62 and the levers associatedtherewith on the pivots 68 from exterior of the control body I0. Forthis purpose, the side of the control body I0 opposite the boss is potions I24 which are received within fulcrum seats I26 formed on the.arms I28 ofa channel-shaped support I30. The support I30 is pivotallymounten'on the arms 64 of the frame 62 by the provision of notchedbearings I32 formed on the arms 64 adjacent the tubular element 66 andproviding support for the opposite ends of a pin I34 extending betweenthe arms I28 of the support I30. Inorde'r to prevent the thermostatlever I6 from displacement, a limit stop pin I36 may provided with anadditional boss 18 which may be hollow and have projecting therethrougha threaded adjusting pin 80 which can be moved into and out ofengagement with the frame portion 10 by an adjusting handle or dial 82.

The dial 82 may be fastened to the pin 80 by means of a headed screw 84having its threaded end inserted in an axial hole in the pin 80, therebeing a coil spring 86 extending between the-underside of the dial 82and the bottom of the hollow boss I8. The dial preferably carries apointer ject from the channel-shaped support I30 into the path ofmovement of the lever I 6.

A tail-piece I38 may extend from the base of the channel-shaped supportI30 and project at an angle thereto in the opposite direction to the 88which cooperates with suitable indicia marked on the surface of thecontrol body I0 to indicate the temperature setting of the device.

The snap-acting leverage carried by the frame 64 comprises threeprincipal parts. The thermostatlever 16, as previously mentioned, has aful-' crum seat in the notched portion 14 of the flange ature arms I28.The tail-piece I38 carries a screw I40 which can be adjusted to bearagainst the tubular element 66 and, by changing the position of fulcrumseat I26 relative to that of fulcrum seat I4, serve to-change thetension of the spring I20 within limits as desired. Movement of thevalve I operating lever I04 may be limited by the proasvascs that forwhich the dial 82 has been set. When the tube 52 of the thermostatbecomes cold due to cooling of the water in the storage tank, the rod 56moves to the right, exerting pressure upon the lever 16 to move it in acounter-clockwise direction about its fulcrum seat 14. Suflicientmovement of the lever 18 in this direction will carry the end 8 of thespring I20 far enough tothe right of the fulcrum seat I26 to enable thespring to exert sufficient force upon the valve operating lever I04, tomove it to the right with a snap action to open the valve 32. After thetube 52 has again become sufliciently heated, the pressure of the rod 06on the thermostat lever 18 is relieved sufflciently to permit movementof this lever in a clockwise direction, returning the end II8 of thespring I22 to its original position and permitting the spring I20 tomove the valve operating lever I04 to the left with a snap action 'andpermitting the valve 84 to close.

By adjusting the dial 82 to move the end of the pin 80 toward or awayfrom the frame 62 the position of the frame 62 and therefore theposition of the thermostat lever I8 may be varied with respect to therod 58 of the thermostat to set the temperature at which the mechanismwill operate. The adjusting dial 82 engages the frame 62 intermediatethe pivots 08 and the stem 90 ofthe thermostat. Thus, any loosenesswhich develops in the pivotal mounting will not afiect the accuracy ofthe adjustment as might be the case if the mounting were otherwisearranged with respect to the dial and thermostat.

The device lends itself readily to assembly of the snap-acting mechanismin considerable quantities and testing thereof in a single test body.When the snap-acting mechanism has been thus by said frame andcomprising a thermostat lever having one end fulcrumed on the end ofsaid frame opposite the pivotal mounting, a support fulcrumed on saidframe at the and opposite said thermostat lever, an operating leverfulcrumed at one end on said support-and extending toward the fulcrumedend of saidthermostat lever, a

tension spring connecting said levers, an operating'arm projectinglaterally from said operating lever for operative engagement with saidvalve member, means adapted for axial movement relative to saidactuating means and being engageable with said thermostat lever adjacentthe fulcrumed end thereof, said axially movable means being responsiveto thermostatic operation for causing movement of said valve member bysnap-action of said actuating means, limit stop means extending into thepath of said levers for retaining said actuating means in said frame,and adjusting means carried by said main body and engageable with aportion of said frame intermediate the pivotal mounting and the. planeof said axially movable means for varying the position of said actuatingmeans relative to said axially movable means.

2. Snap-acting thermostat mechanism comprising a main body having afluid passage, an auxiliary body disposed at one side of said main bodyand having a fluid passage, a valve member tested and its operationchecked in the test body,

it can be assembled in final position in any stand ard control body withthe assurance that further testing will be unnecessary. Considerablespace is conserved by the provision of the offset arrangement of thevalve with respect to the thermostat while retaining the positivesnap-acting operation of the valve. It will be understood that variouschanges may be made in the construction and arrangement of the parts asdescribed and shown herein without departing from the spirit and scopeof the invention as defined in the appended claims.

I claim:

1. Snap-actin thermostat mechanism comprising a main body having a fluidpassage, an auxiliary body disposed at one side of said main body andhaving a fluid passage, a valve member reciprocable in said auxiliarybody and controlling communication between said passages, a framepivotally mounted at one end thereof in said main body. valve actuatingmeans "carried reciprocable in said auxiliary body and controllingcommunication between said passages, 81 frame pivotally mounted at oneend thereof in said main body, valve actuating means carried by saidframe and comprising a thermostat lever having one end fulcrumed on theend of said frame opposite the pivotal mounting, a support fulcrumed onsaid frame at'the end opposite said thermostat lever, an operating leverfulcrumed at one end on said support and extending toward the fulcrumedend of said thermostat lever, a tension spring connecting said levers,an operating arm projecting laterally from said operating lever foroperative engagement with said valve member, pin means engageable withsaid thermostat lever adjacent the fulcrumed end thereof and beingresponsive to thermostatic operation for causing movement of said valvemember by snap-action of said actuating means, a limit stop carried bysaid frame and extending into the path of said operating lever, saidlimit stop having an aperture through which a portion of said pin meansslidably extends, a second limit stop carried by said support andprojecting into the path of said thermostat lever, said limit stopscooperating to retain said actuating means in said frame, and adjustingmeans carried by said main body and engageable with said frame forvarying the position of said actuating means relative to said pin means.

VICTOR

